A coupling between a conduit and an equipment opening typically involves a tubing connection to the conduit on one end and a self-sealing male pipe thread on the other end. The male pipe thread is designed to be engaged with a female pipe thread on the equipment. Unfortunately, it is all too common for the female threads in the equipment opening to become damaged, such that a sealed connection is no longer possible.
U.S. Pat. No. 4,003,835 discloses a fitting for use as a replacement in a carburetor that has substantially entirely stripped threads in the fuel inlet. A smooth, cylindrical, resilient member is expanded into engagement with the stripped thread surface. The fitting in the Johnson Patent is not usable where a substantial amount of the damaged female threads is still in place, as a resilient seal member would not adequately seal against existing threads. In addition, no means is provided to hold the inner member for relative rotation with respect to the outer fitting. The Johnson fitting is useable only in low pressure applications, such as the carburetor fuel line application disclosed (&lt;10 p.s.i.).
Thus, a need presently exist for a coupling member that is usable in high pressure application and/or where a substantial amount of the female threads remain in the equipment opening but a metal-to-metal pipe thread seal is no longer possible.